Grinding wheel



June 9, 1954 J. ROBERTSON, JR 3,136,100

GRINDING WHEEL Filed July 11, 1962 INVENTOR, JOHN ROB JR.

United States Patent 3,136,100 GRINDING WHEEL John Robertson, Jr., Princeton, Mass., assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Filed July 11, 1962, Ser. No. 209,169 5 Claims. (Cl. 51-209) This invention relates to a grinding wheel and a permanently aflixed mounting means for the same which is so simple and which can be made so inexpensively that it can be discarded with the stub of the wheel after the latter has worn down so that it is no longer useful. The throw-away mounting means is assembled with a grinding wheel having a depressed center and is made of two parts, namely, a threaded element which is fitted through from the front or working face side of the wheel to extend rearwardly through the center hole thereof and a rear flanged hub portion adapted to be mounted on the extended portion of the threaded element and centered on the rear side of the wheel.

Illustrative of the cheapness with which the construction may be made, it consists of only two parts which may be produced by die casting. It is of fundamental importance that the rear member has an outer annular flange adapted to be placed in firm contact with the back side of the wheel and give it a solid support, and the rear flange of this rear member is so shaped that the aforesaid depression formed centrally in it will always be deeper than the recessed center formed in the wheel. In this manner, regardless of the tolerance permitted in the manufacturing of the wheel, there will always remain a space between the inside face of the rear member and the wheel surface when the outer flange is in contact with the rear face of the wheel and the depressed central portion of the wheel is disposed in the central depression of the rear member. This space, which exists within the confined portion between the depressed rear flange of the rear member and the depressed portion of the wheel, is then filled with a suitable adhesive, preferably a resin, which solidifies to tion.

In actual practice, it has been observed that the adhesive or resin filler provided as above described not only serves to adhere the rear flange element assembled to the wheel, but when such resin or adhesive becomes solidified, it serves as a solid spacer. The spacer is automatically adjusted to fit between the wheel and the rear member 'so that when a front threaded element or nut is screwed tightly onto the driving spindle, the wheel is held firmly engaged between the rear member and the nut element. The ability to accommodate the maximum tolerance in wheel production within the central depression of the rear member or hub is an important feature of the invention and contributes greatly to the successful manufacture and use of a' relatively inexpensive wheel and mounting means therefor.

In brief, the present invention comprehends a most efficient back pad or supporting 'mount for reinforced,preferably organic bonded, recessed hub wheels by the use of a novel cushioning material in combination with the back pad, the wheel and the cooperating attaching means. The cushioning material, i.e., the bedding adhesive or resin, assures a support of the proper rigidity with exact and complete uniformity of contactarea between the wheel itself and the mount. The result is a more eflicient stress distribution and, in turn, a stronger product or a product of at least equal strength with conventional combinations, but with less bulk and at an appreciably lower cost. The mounting of this invention, as explained above, also elimadhere and hold the parts in the desired assembled relaa inates the effect of dimensional variations which are com- "ice mon to wheels of this type. It is a particular feature of the invention that the cushioning material, notably, the adhesive or resin, will take the form of the depression defined by the wheel and the back pad or rear member. Heretofore recessed hub wheels employed two types of supports, namely, a flexible type and a rigid type. The flexible type had a band of material formed as the lands ofthe wheel mount which because of its flexibility would give under pressure. This would allow the wheel to fit without causing any major stresses occasioned by the tightening of the mounting. It had the disadvantage of deflecting under grinding stresses and, therefore, never fully supported the wheel. The second type or rigid support overcame this disadvantage. However, it offered a further disadvantage of its own because stresses, even to the extent of cracking the wheel, would sometimes occur in the wheel due to tightening of the front threaded member or nut. This cracking under stress was caused by the variation in the dimensions of both the rigid bodies, namely, the rear and front members of the mounting, which seldom matched precisely. I have discovered that if a pad or rear member is designed to insure wheel and land contact in every case, the depth of the recess in the rear member must be as deep as the production tolerance allowed for the depth of the most extreme wheel recess. However, in making use of such a structure, unless all aspects of my invention are used, a wheel with a shallower central recess will have more or less additional stresses added to it by the threaded front element or nut when the same is screwed home, thereby forcing the wall of the recess in the wheel to be in contact with the pad or rear element which may be spaced somewhat from the back side of the wheel when any tolerance other than the maximum production tolerance is encountered in a wheel.

The present invention eliminates the disadvantages of both of the conventional mountings above described while maintaining their advantages. .This is accomplished by supplying an economical cushion,'i.e., bedding, as the adhesive or resin, which conforms in shape to both the central recess in the pad and the wheel and, at the same time, is sufliciently rigid to support the wheel in grinding. The adhesive or resin constituting the bedding or cushion preferably flows under heat or pressure or both and fills the .space between the inside or front wall of the recess in the Formulation of adhesive or cushioning material Material Source Parts by Weight Polyester resin No. 1095 with Cobalt Naph- Naugatuck..

thenate. Tale 100 Methyl Ethyl Ketone Peroxide Cadet 1. 5

Thin depressed center resinoid bonded wheels provided with mountings in accordance with this invention were compared with similar wheels with heretofore known commercial mountings on the high speed rotary side pressure test and in every instance wheels mounted in the manner I teach proved entirely satisfactory and elficient, i.e., the

'mounting means performed effectively until the wheel was worn down, at which point both the wheel and mounting could be economically discarded.

construction which does not depend solely on the strength of the material of the mounting and the adhesive connection for driving the grinding wheel.

Another object of the invention is to provide a structure in which it is possible to properly support the wheel, especially when pressure is applied near its periphery, which causes it to flex. This continued pressure and flexing encountered in use of conventional mountings often results in weakening such known mountings and thereby produces a failure of the adhesive or loosening of the molded mounting.

It is additionally an object of the invention to provide a preattached and properly aligned mounting attached to a grinding wheel as a unit.

Also, it is an object of the invention to provide a grinding wheel with a self-aligning mounting which may be coupled to a drive means to apply pressure between elements' of the mounting to properly clamp, support and drive the grinding wheel therebetween.

Furthermore, an object of the invention is to provide a continuous bearing surface between the mounting and the grinding wheel to assure a uniform stress distribution.

Still another object is to provide an adhesive-type hardenable bedding material between the mounting and the grinding wheel which sets up to assist in permanently holding the mounting attached to the grinding wheel.

An important object of this invention is to provide a mounting which will accommodate the most extreme tolerance permitted in the manufacture'of the depressed center or hub portion 'of the known depressed center type of grinding wheel.

Again, it is an object of this invention to provide a mounting having a continuous annular mating land adjacent its periphery for contacting and rigidly supporting the grinding wheel from the back side throughout an area located beyond the depressed hub portion of the wheel and beyond the periphery of the elements of the mounting means which form the wheel clamping portion thereof.

Essentiallythe invention comprises a mounting for depressed center grinding wheels having two different opposed supporting members each of which is provided with a circular flange. One of the flanged pieces has an axially extending hub extension which is internally threaded and whose external diameter is of a size to neatly fit the hole in the center of the grinding wheel. The extension is adapted to be inserted into the hole from the front side of the wheel and is of a length to project beyond the rear surface of the hub of the grinding wheel. A flange formed integral with this member is fixedly attached to the front side of the wheel within the recess formed by the depressed center with an adhesive that solidifies in place.

Onto the rearwardly projecting portion of the extension is fitted a larger annular flange or supporting member which is axially aligned thereon. The rear supporting member has a depressed configuration which is deeper than the deviation in the rear wall of the depressed configuration of the hub portion of the grinding wheel. The

. g r 4 provided so that the shoulder of the shaft contacts the bearing shoulder of the supporting member when the front flanged member is screwed onto a threaded extension of the shaft thereby applying a clamping pressure to the grind ing wheel between the front and rear supporting elements.

In the accompanying drawings is shown the preferred embodiment of the invention in which,

FIG. 1 is a rear plan view of the grinding wheel and attached mounting.

FIG. 2 is a side elevation exploded to show the main components before attachment to one another, and

FIG .3 is a vertical section taken on line 33 ofPIG- URE 1 showing the mounting attached to the depressed center grinding wheel.

Referring to the drawings, a grinding wheel 10 has a central depressed center or hub portion generally denoted 12 comprising a surface 14 on the front of the wheel and an opposite surface 16 of similar shape on the back side which is substantially parallel to surface 14. The grinding portion of the wheel extends laterally from the hub and has a front face 13 and rear face 20. As shown the surfaces 14, 16, 18 and 2(l'all lie in planes which are parallel to each other but it is obvious that the grinding portion can be cupped or have any other conventional shape.

The wheel has a central hole or aperture 22 of predetermined size which is disposed centrally in the depressed center or hub portion 12, the wall of the aperture being 7 disposed at substantially right angles to the surfaces 14 inside diameter of the annular portion of the rear support I supporting member which void may be filled with an ad hesive of a type which hardens to a rigid condition. The periphery of the rear supporting member is finished to have a flat circular land or surface which contacts the surface on the back side of the wheel beyond the periphery of the depressed hub.

The rear supporting member has a bearing shoulder surrounding an aperture through which the shouldered shaft of the driving means passes. .Such a construction is and 16.

A mounting assembly is provided for supporting and driving the grinding wheel. The mounting consists of an internally threaded member 23 having a cylindrical portion 24 extending from and integral with a flange 26. The flange has a thickness that is less than the depth of the recess or depression forming the hub in the grinding wheel. The cylindrical portion 24 of member 23 has an external surface 28 which closely fits the aperture 22 in the hub portion of the grinding wheel and extends through the hole to project beyond the surface of rear wall 16 of the depressed hub.

Cooperating with member 23 is a rear supporting member 30 having an aperture 32 for engaging on the extending cylindrical portion of member 23. The supporting member 30 has an enlarged depressed shape similar to the shape of the depressed hub, but deeper and of larger diameter than the shape of the rear wall 16 of the depressed hub over which it fits.

The rear support member has a wall 34 connecting its central portion with a peripheral flange 36 which contacts the rear surface 20 of the wheel beyond the periphery of the depressed hub portion 12. The rear support member is formed with a recess or depressed portion enclosed within wall 34 which is of a depth greater than the distance between wall 20 and theplane of wall 16 which is the depth of the depression of the hub portion 12 of the wheel as measured between surfaces 16 and 20 thus leaving a space or void between the front or inside surface of wall 34 and the rear wall 16 of the wheel when the rear support member is fitted onto the wheel. Concentric with the aperture 32 is another surface 40 in the member 30 which is provided fora purpose that will appear more fully below. On the supporting member 30 is a shaped portion 50 to accommodatea wrench for removing the mounting assembly 24 relative to the threaded drive shaft 48.

In practice, it has been found that due to variations in contour between grinding wheels and of mountings manufactured separately, it is practically impossible to match or make complete contact between their surfaces to provide a good bearing support. Therefore, the invention avoids this difliculty by providing, as stated before, a recess surface of suflicient depth to always provide a void between surface 16 and wall 34, which void is adapted to be filled with the bedding material 38, which is of such a nature as to conform to the shape of both the grinding wheel and mounting as the rear support member is fitted onto the wheel during the manufacturing assembly operation.

Additional material 38 is also located between the front surface 14 and flange 26. It provides a continuous, permanent bearing surface and has suflicient adhesive qualities which prevent the mounting assembly 23-30 from being removed once it has been attached to the grinding wheel. The material 38 is semi-fluid or at least plastic initially but hardens once the parts 23 and 30 are fitted onto the wheel. In this way a completely uniform support is established and maintained throughout the life of the grinding wheel and yet this means provides for quickly attaching or detaching the wheel from its drive means. It will be seen that very little if any of the adhesive-type bedding material 38 is present between the continuous land or surface 36 of the supporting member 30 and the surface so that this structure provides for direct contact and support of the wheel without permitting any bending or distortion of the grinding wheel by the mount- Many different types of materials may be used to attach the mounting assembly 23-30 to the grinding wheel vwhich will set up sufficiently to properly support it.

Such material may be filled or unfilled epoxy or polyester resins, as above described. An example of a most success ful material contains 100 parts by weight of polyester resin with cobalt naphthalene, 100 parts by Weight of talc and 1.5 parts by weight of methyl ethyl ketone peroxide. This material will initially be a paste at room temperature. It is applied to both surfaces 14 and 16 of hub portion 12 in a bead of proper size required for each of the front and rear flanges 26 and 34 respectively. The nut 23 is then inserted in the aperture 22 from the front side of the grinding wheel and the supporting member 30 is placed over the extension of the nut 23, which automatically aligns the mounting assembly. Thereafter, the two are forced together under sufficient pressure to spread the material 38 until the land or annular surface 36 of the rear member 30 makes complete contact with the adjacent surface 20 of the wheel and the parts 23 and 30 are maintained under slight pressure until the material 38 has set up.

After the material 38 has solidified it bonds parts 23 and 30 to the wheel and the preattached mounting and the grinding wheel or cutting tool can now be quickly attached onto a driving spindle as a unit by screwing threaded member 23 onto the end 48 of the drive shaft. The surface 40 fits closely around the periphery of the shaft and as the part 23 is tightened on threads 48, part 30 is driven home against shoulder 44 on the drive shaft. The final tightening can be completed by using a wrench on the squared-off portion 50 of part 30 for this purpose but the threads 48 normally coact with 23 to be self tightening when the wheel is driven. When properly mounted on the drive shaft the grinding wheel or cuting tool is positively clamped between the flange 26 and the central area of the wall 34 without depending solely on the adhesive qualities of the material 38 to hold it in driving relation. This prevents the mounting from shifting or loosening relative to the wheel during use and even if the adhesive connection fails, the wheel cannot break free of its mounting. While the wheel is firmly clamped at the center portion of the hub, it is apparent that the land 36 provides a somewhat flexible backup support for the rear of the wheel which engages the wheel beyond the periphery of the depressed hub portion and beyond the positively clamped areaof the hub which is engaged between flange 26 and wall 34.

Because the mounting can be produced cheaply and economically, as by die casting if desired, it may be thrown away with the worn-out grinding wheel or cutting tool and replaced quickly with another complete grinding wheel unit, resulting' inv savings of time and consequently of labor costs in mounting a new wheel.

There has thus been provided by this invention an economically-produced grinding unit with pre-attached drive means, which has many practical advantages in that it provides good support and inherently compensates for dimensional variations encountered in the normal manufacture of reinforced grinding wheels of the depressed center type. Such a mounting also maintains the same uniform support throughout the life of the grinding wheel, utilizes an improved application of clamping stresses more uniformly. This construction additionally prevents fracturing of the grinding wheel by eliminating distortion of the wheel during mounting and the entire wheel assembly is therefore safer to use. It further minimizes the wasteful down time necessarily encountered during wheel changes when replacing a worn-out unit.

It has been suggested above that wheels of diiferent shapes other than the planar configuration here shown, may be fitted with the hub assembly of this invention to advantage. It is suggested that many other and different modifications may be made of the preferred and described embodiment of the invention and it is to be understood that all matters hereinbefore set forth or shown in the accompanying drawings are to be interpreted as illustrative only and not in a limiting sense.

I claim:

1. An abrading tool for mounting on a rotatable shaft having a reduced threaded end portion and shoulder thereon comprising, a grinding wheel with a depressed center, said depressed center having a central raised surface of predetermined height above its back side, a depressed surface opposite said raised surface on its front side and a centrally disposed aperture therein, a flanged member having an internally threaded portion extending through said grinding wheel and beyond said raised surface, a supporting member centered on and by the portion of said flanged member extending beyond said raised surface, a continuous land adjacent the periphery of said supporting member contacting a portion of the grinding wheel surface of said back side beyond the extremities of said raised surface, a recessed surface in the supporting member disposed relative to said land of a depth greater than the height of said raised surface, an initially soft hardened adhesive-type bedding material between said recessed surface and said raised surface and between said flange member and said depressed surface and means on the supporting member for supporting engagement with said rotatable shaft and said shoulder thereon for applying clamping pressure on the grinding wheel between said flanged member and the supporting member.

2. An abrading tool for mounting on a rotatable shaft having a reduced threaded end portion and shoulder thereon, comprising, a grinding wheel with a central depressed center, said depressed center having a central raised surface of predetermined height above its back side, a central depressed surface opposite said raised surface on its front side, and a centrally disposed aperture thereon, an annular flanged member having an internally threaded portion in said aperture and extending beyond said raised surface, a supporting member axially aligned on and by the external surface of said flanged member extending beyond said raised surface, a continuous annular land adjacent the periphery of said supporting member contacting a portion of the grinding wheel surface of said back side beyond the diameter of said raised surface, a recessed surface in the supporting member disposed relative to said annular land of a depth greater than the height of said raised surface, an initially soft hardened adhesive-type bedding material between said recessed surface and said raised surface and between said flanged member and said depressed surface and means on the supporting member for supporting engagement with said 7 rotatable shaft and said shoulder thereon for applying clamping pressure on the grinding wheel between said flanged member and the supporting member.

3. A unitized tool 1 for mounting on a drive shaft having a reduced end' portion with attaching means and a shoulder thereon comprising a cutting tool with a central hub portion, said hub portion having a first shaped surface of predetermined height above its; back side, a second shaped surface opposite said first shaped surface of a predetermined lesser height above its front side, and a centrally disposed aperture in said tool hub portion, a flanged member having a portion provided with means to engage said attaching means extending through said hub portion and beyond said first shaped surface, a supporting member axially aligned on and by the portion of said flanged member extending beyond said first shaped surface, a continuous surface adjacent the periphery of said supporting member contacting a portion of the cutting tool surface of said back side beyond the extremities of said first shaped surface, an elevated surface in the supporting member disposed relative to said continuous surface of a height greater than the height of said first shaped surface, an initially soft but ultimately hardened adhesive bedding material between said elevated surface and said first shaped surface, and between said flanged member and said second shaped surface, and means on the supporting member for supporting engagement with said drive shaft and said shoulder thereon for applying clamping pressure on the grinding wheel between said flanged member and the supporting member.

4. A drive mounting for a grinding wheel with a depressed center, said depressed center having a central raised surface of predetermined height above its back side, a depressed surface opposite said raised surface on its front side and a centrally disposed aperture therein comprising a supporting member extending beyond said raised'surface, a continuous land adjacent the periphery of said supporting member contacting a portion of the grinding wheel surface of said back side beyond the ex tremities of said raised surface, a recessed surface in the supporting member disposed relative to said land of a depth greater than the height of said raised surface, a flanged member for contact with the opposite side of said grinding wheel and an initially soft hardened adhesivetypebedding material between said recessed surface and said raised surface.

5. A drive mounting for a grinding wheel with a depressed center, said depressed center having a central raised surface of predetermined height above its back side, a depressed surface opposite said raised surface on its front side and a centrally disposed aperture therein comprising a supporting member extending beyond said raised surface, a continuous land adjacent the periphery of said supporting member contacting a portion of the grinding wheel surface of said back side beyond the extremities of said raised surface, a recessed surface in the supporting member disposed relative to said land of a depth greater than the height of said raised surface, a flanged'member for contact with the opposite side of said grinding wheel, mating means for axially aligning said supporting member on said flanged member and an initially soft hardened adhesive-type bedding material between said recessed surface and said raised surface and between said flanged member and said depressed surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,810,239 ,Burleigh Oct. 22, 1957 2,823,496 Winter Feb. 18, 1958 3,040,485 Tocci-Guilbert June 25, 1962 3,041,797 Mofliy July 3, 1962 

1. AN ABRADING TOOL FOR MOUNTING ON A ROTATABLE SHAFT HAVING A REDUCED THREADED END PORTION AND SHOULDER THEREON COMPRISING, A GRINDING WHEEL WITH A DEPRESSED CENTER, SAID DEPRESSED CENTER HAVING A CENTRAL RAISED SURFACE OF PREDETERMINED HEIGHT ABOVE ITS BACK SIDE, A DEPRESSED SURFACE OPPOSITE SAID RAISED SURFACE ON ITS FRONT SIDE AND A CENTRALLY DISPOSED APERTURE THEREIN, A FLANGED MEMBER HAVING AN INTERNALLY THREADED PORTION EXTENDING THROUGH SAID GRINDING WHEEL AND BEYOND SAID RAISED SURFACE, A SUPPORTING MEMBER CENTERED ON AND BY THE PORTION OF SAID FLANGED MEMBER EXTENDING BEYOND SAID RAISED SURFACE, A CONTINUOUS LAND ADJACENT THE PERIPHERY OF SAID SUPPORTING MEMBER CONTACTING A PORTION OF THE GRINDING WHEEL SURFACE OF SAID BACK SIDE BEYOND THE EXTREMITIES OF SAID RAISED SURFACE, A RECESSED SURFACE IN THE SUPPORTING MEMBER DISPOSED RELATIVE TO SAID LAND OF A DEPTH GREATER THAN THE HEIGHT OF SAID RAISED SURFACE, AN INITIALLY SOFT HARDENED ADHESIVE-TYPE BEDDING MATERIAL BETWEEN SAID RECESSED SURFACE AND SAID RAISED SURFACE AND BETWEEN SAID FLANGE MEMBER AND SAID DEPRESSED SURFACE AND MEANS ON THE SUPPORTING MEMBER FOR SUPPORTING ENGAGEMENT WITH SAID ROTATABLE SHAFT AND SAID SHOULDER THEREON FOR APPLYING CLAMPING PRESSURE ON THE GRINDING WHEEL BETWEEN SAID FLANGED MEMBER AND THE SUPPORTING MEMBER. 